Bio‐energy for India• Current situation vis-à-vis all energy usage• Bio-energy versus other renewable energies• Routes of conversion• Liquid fuels (called Bio-fuels generally)• Improvements in solid fuel use• Environmental-international issues• Way-forward

H S Mukunda, IIScmukunda@cgpl.iisc.ernet.in; http://cgpl.iisc.ernet.in

Current situation ‐ all energy usage• Coal – 500 mmt/y – Centralized electricity gen• Diesel (HSD) – 50 mmt/y – Heavy transport (Road + railroad)• Fuel oil – 12 mmt/y – Standby power gen (Comp. ignition engine) + furnaces• Gasoline – 12 mmt/y – Light motor vehicle (LMV) transport• LPG – 10 mmt/y – Domestic cooking + LMV• Kerosene – 12 mmt/y – Domestic cooking + transport (illegally)• Biomass (firewood, agro-residues, cow-dung) – 500 mmt/y – largely for cooking, heat and energy mmt/y = million metric tonnes per year

Fuel Imported, how much Efficiency of useCoal ~ 5 – 10 % 32 % average, 37 % peak

(elec)Equivalent heat ~75%

Diesel, Gasoline, FO, Kerosene

Based on 70 % crude import (30 billion USD)

Diesel, FO, Gasoline – goodKerosene – average to poor

LPG ~ 60 – 70 % domestic heatBiomass* - 15 % average, 30% peak

Fuel import and efficiency of use

FO = Furnace oil or fuel oil,

* Biomass - Firewood, Agro-residues, cow-dung

Bio‐energy versus other renewable energies

Energy sources and comparison

Source Purpose FeaturesSolar thermalPhoto Voltaics

heat electricity

Intermittent,PLF ~ 30 %

Wind electricity Intermittent,PLF ~ 30 %

Micro-hydel electricity PLF ~ 50 to 70 %

Biomass liquid fuel, foodheat, electricity, chemicals and fiber

Stored solar energy available on demand, PLF ~ 95 %

PLF = Plant load factor = hours used per year / 8760 hours

Bio‐energy as renewable energySure, Who says No? …………Is it really for so sure?Generally, most people including bureaucrats suffer from fourth source syndrome. They wish to begin by SPV, go through Wind (both of which are intermittent), allow hydro but ignore bio-energy most of the time! Mark Jacobson, Stanford University and Mark Delucchi, Uni California, Davis in Scientific American, November 2009…Wind and Solar photovoltaics adequate as renewable energy adequate in 2030. Widely discussed, trashed, argued back…..They think biomass is a problem and solution is SPV and Wind. Even Google’s energy plan is along these lines!

It appears to many of us that biomass is the solution, and could be a cheap one at that,

Let us review some facts

…Reviewing facts..• We already noted that in India the amount of biomass used

for cooking is 500 mmt every year at 10 to 20 % eff and that the amount of coal used for power generation is 500 mmt.

• Roughly stated, food for 650 million people is cooked on biomass!

• World over about 2.5 billion people cook on biomass. In African, in many countries, 95% dependence is on biomass!

• Will this situation be altered in the next thirty years? It is unclear how. Also, really, why one should move away from biomass. Cannot we not solve the problems related to biomass?

House‐hold cooking on biomass… In India ~465 mmt/year (Coal use ~ 500 mmt/year)

100+ mmt of agricultural wastes for cooking fuel/electricity

20+ mmt of plantation waste for electricity

33+ million Hectares of waste land that could lead to 33 + mmt of non-edible oil (equivalent of 25 to 27 million tonnes of HSD) and 130 mmt of solid biomass. This promises at least 60 million jobs (unskilled + skilled) in the tree culture of the waste land. The choice of waste land for bio-oil avoids the fuel vs. food debate in the USA and other countries. These jobs can be arranged to provide monthly remuneration that eliminates farmer suicides due to agriculture-related problems

40000+ tonnes per day of Urban solid waste that could become briquetted fuel or electricity.

Liquid wastes – sewage, industrial wastes from food processing industries, amounting to 7 million metric cubic meters per day.

Only a few % has been capitalized upon. Much can be done and needs to done to help the economy straighten up.

In India - Bio-wastes…how much?

What solid fuels? What features?Material Examples Density, kg/m3 Ash, %Coal - 1200 5 to 40Agricultural residues

Rice huskGround nut huskBagasseSugarcane tops

10010010050

20326

Plantation residues WoodCoconut shellCoconut frond

400 to 7001100300

115

Urban solid waste Mix 200 to 300 ~10

All have C-H-N-O elements; Moisture is inherent to the extent of 50 %There are some in-organics, For example, rice husk ash has 95 % Silica; Others have Al-oxide, Mg-oxide, etc in different proportions

Routes to conversion – 95 % thermo‐chemical conversion

Technology Fuel/ capacity SFCkg/kWh

Steam Biomass, fossil fuel• < 100 kW• 100 - 500 kW• 500 - 2000 kW• ~ 4000 kW

~ 6 -8 kg/kWh~ 4 - 6 kg/kWh~ 2 - 3 kg/kWh~1.5 – 2 kg/kWh

Gasification•Dual fuel and gas alone operation•Gas turbine with recuperater

Agro residues• < 100 kW• < 100 - 500 kW• ~ 1000 kW

~ 1.2 – 1.5 kg/kWh~ 1.0 – 1.3 kg/kWh~ 0.8 - 1.0 kg/kWh

Stirling engines Can be agro residues• < 100 kW

< 1.5 kg/kWh

IGCC Agro residues> 2000 KW ~ 0.7 – 0.8 kg/kWh

Broad performance details

Liquid fuels from biomass– Bio-fuels

Liquid Fuels• Non-edible oil from oil seed bearing trees (1st Gen)• Alcohols from sugarcane and biomass (1st Gen)• Pyrolitic oil through high temperature processing• Hydrocarbons from gasification – F-T synthesis and

other processes

• A large number of trees store in their seeds, starchor oils. Some of these are non-edible. They can be usedfor power generation. If we can produce excess ofedible oils, they can also be used (with some controls)

• These are Palm oil (Malaysia), Rape seed oil (Germany),Soybean Anderouba, Soumarouba (Brazil), Jatropha,Jojoba, Pongemia, Cashew, Mohua, Sal, Neem (Indiaand other countries)

Crop species Output oil tonnes /h

Palm oil 5.0Coconut 2.2Brazil nuts 2.0Jatropha 1.6Jojoba 1.5Rapeseed 1.0Groundnut 0.9Sunflower 0.8Pongemia 0.8Soybean 0.4

Typical oil output from various trees

Note the wide variation in the productivity of various species. ThisProvides motivation to pursue growing species with higher output.

Solid residuesconstitute 70 – 80 % of the feed stock

Liquid fuels…• The seeds should be dried, used in an oil expeller to extract

the oil, filter the oil, esterified by adding methyl or ethylalcohol (depending on what is cheaper and available) – about 5%; this also reduces the emissions when used in engines.

• The oils have a calorific value about 5 to 10 % lower thandiesel. They work very well in compression ignition engines.The amount required for producing electricity is 275 to 330ml/kWh in comparison to 250 to 300 ml/kWh for diesel.

• Alcohols are produced from sugar juice (or others in whichstarch should be converted to sugars) through the process offermentation. They have about 60 % energy compared tofossil fuels

Improvements in solid fuel use

Conventional stoves: Efficiency and emissionsBhattacharya et al (2002) have tested efficiencies and emissions from 24 different wood and charcoal stoves of east Asian origin.

Thailand, η 14%, CO 1.7 g/MJ

India, 25.2 %2.6 g/MJ

Malaysia, 9.5%28.7 g/kg fuel

Thailand, 12%1.6 g/MJ

Nepal, 10.5 %CO 136 g/kg fuel

Lao, 14.3%27.3 g/kg fuel

Vietnam, 15%38.6 g/kg fuel

Philippines, 12%28.6 g/kg fuel

Fuel and Power vs. time in an conventional biomass stove

When biomass is loaded, power Increases a little afterwards, since it takes a few seconds to a few minutes depending on the size for the wood to heat up and begin to give off volatiles. When all the volatiles are consumed, biomass becomes char whose weight is about 20 to 25 % of the biomass. After this char oxidation occurs.

New methods for– Domestic cooking/heating needs

Principles  ‐ first technique – fire and forget/control1. Burn from top to bottom of a pile instead of bottom to top 

(practiced for several thousand years)2. Recognize that this is a two stage combustion process in 

which sub‐stoichiometric  combustion  occurs first and then combustion of the gases is completed at near‐stoichiometric conditions. The first phase is also termed gasification. Such devices are called “Gasifier Stoves”

3. The power output is proportional to the air flow rate. Hence, controlling it helps vary the power.

Fuel is in the form of pellets – 8 to 10 mm dia and 30 to 50 mm long

Air from the bottom –primary air – produces combustible gas over the solid fuel bed

Air at the top region –secondary air – burns up the gas at near stoichiometricproportions

The gasification stove.

Power variation in a gasifier stove.(mass loss varies linearly – power is nearly constant)

Why is the power nearly constant in gasifier mode?

• In the gasification process, excess carbon is always present in the form of charcoal.

• Only that amount of carbon that is required to cause the reduction reactions is consumed.

• The propagation of the thermal profile against the flow of air occurs at a rate to reach equilibrium composition or conversion.

• With the use of sizes of biomass not widely different, the amount of biomass covered by the thermal profile is also nearly same.

• This keeps the consumption rate constant.

Another approach• Principle – Ejector induced gasification based

stoves – continuous fuel feed – can deal with firewood

• An ejector induces an air current below it. This is made use of to draw air through a fuel bed horizontally located

• The use of partial blockage helps the gasification process.

• The char bed on the grate allows gasification process to be completed.

• Controlled air flow through the grate from the bottom section helps char conversion and maintain a high temperature in the fuel preparation zone

10 kg/h stove functioning at optimum conditions

EIGAS stove at 30 kg/h (120 kWth)

It runs on 2 x 12 V x 1 amp two stage fans

Stove Fuel g CO g PM g CO g/MJ PM g/MJThree stone Fire 1118 56 2363 3.13 42.27Ghana Wood 996 50 4287 3.14 68.3220L Can Rocket 733 15 1289 1.28 15.12Wood Flame Fan 626 9 48 0.90 0.48Wood Gas Fan 459 7 27 0.95 0.20Mali Charcoal 674 113 260 10.48 2.80Gyapa Charcoal 694 135 587 12.16 6.52Indian VITA Test 1 1135 38 1490 2.09 27.06T-LUD 933 25 694 1.67 10.36Institutional 310 Rocket 483 6 414 0.78 3.20Lutfiyah's Improved Stove 823 16 1231 1.22 16.21T-LUD 1296 18 437 0.87 9.06BP Stove (IISc) 380 4.5 6 0.75 0.06EIGAS – 1 (IISc) 400 7.2 9.6 1.12 0.1

Comparison of stoves for bringing to boil 5 liters of water

Increase in efficiency appears synonymous with reduced emissionsThis is the idea of HELE (High Efficiency Low Emission) design

Environmental‐international issues

E‐I issues• Indoor air pollution  (avoided by Chimney based 

stoves)• Indoor and environmental pollution (avoided only 

by fan based designs)• Biomass as an aid to reduce Green House Gas 

emission• Black carbon and GHG emission – stoves, large 

scale biomass burning

Biomass as an aid to reduce GHG• GHG emissions are very significant from fossil fuels –

largely controlled by fossil fuels – transportation and coal based power generation. 

• Solutions for power generation – using CO2 from exhaust gases to produce industrial products (cheap) or storing it underground, etc.

• Co‐firing with biomass in coal power stations is one route. • Solutions for transportation are sought in liquid bio‐fuels.• We need to remember that this route leads to 70 to 80 % 

solid residues.

Biomass as an aid to reduce GHG• Biomass is intrinsically C +/neutral/‐ depending on (usage –

storage). Growing biomass reduces GHG through absorption of CO2. 

• Simply growing biomass is inadequate. CO2 absorption rate is higher during growth.  Harvesting, efficient usage for energy would be a meaningful route.

• Better carbon sequestration is sought by incorporating the residual char (Bio‐char) into the soil with benefits – GHG reduction and nutrient conservation.

• Extensive practice is argued to lead to a definitive C negative solution in the most economical manner

Black carbon issue?Soot is an amorphous-shaped particle emitted into the air during fossil-fuel combustion, bio-fuel combustion, and biomass burning.

Soot particles contain black carbon, organic carbon, and smaller amounts of sulfur and other chemicals.

Soot from diesel combustion usually appear black because it contain a high fraction of black carbon, which absorbs all colors of visible light, preventing such light from reaching our eyes.

Soot from bio-fuel burning is brownish because it contains a higher ratio of organic carbon to black carbon than diesel soot, and organic carbon absorbs short light wavelengths preferentially, appearing brown.

…. Called therefore Brown cloud problem… (an Indian Scientist, V Ramanathan at Scripps institution of Oceanography is involved in this subject as well. An UNEP document An integrated assessment of black carbon and tropospheric ozone, UNEP/GC/INF/20)

Wheat field burning after harvest Punjab – 5500 km2 May 2005

Rice field burning after harvestPunjab – 12,600 km2 Oct 2005

From an NRSA  paper, Current Science, June 2006 

Way‐forward• There are a number of issues both intrinsic and externally 

imposed on energy and environment.• Increasing efficiencies, avoiding arbitrary burning and getting 

fuels from wastes all contribute to reducing the emissions internal and environmental while meeting energy needs.

• Beyond rhetoric and posturing, greater recognition and understanding are required to deal with substantive issues

• Mainstreaming biomass as a fuel of significance is one of the very important aspects. Awareness and education are central to this approach.

• Education whose purpose is understanding of fundamentals of bio‐energy is central to the way‐forward.

………….Thanks